Estradiol-17 beta suppresses testicular development and stimulates sex reversal in protandrous black porgy, Acanthopagrus schlegeli

Two year old black porgy (Acanthopagrus schlegeli) fed a diet containing 4.0 mg kg(-1) of estradiol-17 beta (E(2)) for 5 months had significantly lower GSI than the control group during the spawning season. E(2) suppressed testicular development, spermiation and plasma testosterone (T) and 11-ketotestosterone (11-KT) and stimulated ovarian development, vitellogenesis and sex reversal. Spermiation in the control group occurred in January and February with the concentrations of 1.08-1.36 x 10(10) sperm ml(-1) of milt. Higher plasma T and 11-KT, but lower E(2) levels were detected in the spermiating fish (control group). Higher plasma E(2) levels were detected in the sex reversing black porgy during the pre-spawning season. A sharp rise in plasma 11-KT and a drop in T levels were detected in spermiating fish (control group) from January to February. Plasma 11-KT levels correlated with the testicular development and spermiation. The data suggest that E(2) plays an important role in controlling the sex reversal of black porgy.